Anticorrosive gasoline



2,728,645 ANTICORROSIVEVGASOLINE Samuel Clyde Vaughn, Berkeley, Calif.,ass'ignor to Tide Water Associated Oil Company, San Francisco, Calif., acorporation of Delaware No Drawing. Application April 1, 1952, SerialNo. 279,924

6 Claims. (Cl. 44-450) The present invention relates to corrosioninhibitors for gasolines having high octane ratings, and especiallythose gasolines designed for use in aircraft type internal combustionengines. More particularly, it relates to corrosion inhibitors formed asreaction products from alkyl acid phosphates and certain amines, and,which are compatible with other desirable additives. It further relatesto anti-corrosive gasoline and means for producing the same. It alsorelates to the means for manufacturing corrosion inhibitors.

Recently, corrosion inhibitors for gasoline have attained importance asa result of research designed to inhibit corrosion in fuel systems andstorage-tanks, particularly where moist gasoline may come in contact.with' such metals as iron, copper, brass or the like. This type ofcorrosion is caused usually'by the presence of water, and occursgenerally at the water-gasoline,interface. Further: more, variouscomponents used in leaded gasolines are thought to be active promotersof corrosion.

The appearance of water as a separate phase in aviation gasolinemay becaused either by entrained water from the fueling pumps used in fuelingaircraft, since these use water displacement to pump the gasoline;or,'by moisture in the air above the gasoline in the fuel tank,- since,at temperatures prevalent in high altitude flying, the moisturecondenses and precipitates.

, Another class of important additives often used in aviation gasolineis composed of certain anti-knock agents designed praticularly for richmixture operation. Foremost among these additives are aniline and itshomologs, such as for example, ethyl aniline, methyl aniline, amylaniline, diamyl aniline, cumidine, and xylidine. These aromatic aminesare very effective for this particular purpose when used in proportionsof about one to three percent of the gasoline, and function as cumenesubstitutes in aviation gasoline blends.

Although corrosion inhibitors and the above mentioned anti-knockagentsfunction excellently when each is used in, the absence of the other,many of the common corro sion inhibitors are not compatiblej therewith.Conse: quently, when many ofthe alkyl acid phosphate-amineneutralization'products conventionally used for anti-corrosion purposesare added to a gasoline containing aniline or a homolog of aniline, an;undesirable .precipitateor haze forms, The deleterious effects ofprecipitates in liquid'fuels are well'recognized, and in this instancethey may form a stoppagein carburetor jets or otherfine orifices as wellas remove a substantial portion ofthe corrosionrinhibitor from thegasoline solution. It will also be appreciated that gasoline.homogeneity is one of the accepted requisites of marketability.

In accordance with the invention, it has been: found that when alkylacid phosphates are reacted, or neutralized, with branched chain dialkylaliphatic amines having 4-15 carbon atoms per alkyl group and in whicheach branchis a methyl group attached to a carbon atom positioned atleast two carbon atoms from the terminal carbon excellent gasolinesoluble corrosion inhibitorsare produced which "ice do not formprecipitates or haze in gasoline solutions containing aniline or itshomologs. Some examples of the aforesaid branched chain dialkylaliphatic amines which are satisfactory for use in the present inventionare suggested as follows:

Di secondary butylamine Di secondary amylamine Di 3-methyl pentylamineDi 2,4-dimethyl hexylamine Di 2,5,8 tri methyl dodecylamine The need formethyl side chains in lieu of longer chains Cir such as ethyl or propyl,for example, is confirmed by the fact that longer side chains do formprecipitates when the reaction product therefrom is in the presence ofaniline or its homologs. In this connection di Z-ethyl hexylamine isunsatisfactory for the reason stated above. Likewise, if the methylgroup is attached to the next to the last carbon atom (i. e. in theso-called iso position) the compounds thus formed produce precipitates.

While certain variations and deviations from the teachings of thepresent invention are encompassed within its scope and spirit, it isnevertheless recommended that the process of manufacturing the finishedgasolines containing desired additives be carried out in specifiedsteps. For example, the order of addition of materials as well as themethod of mixing the components must follow definit patterns.

The amine and alkyl acid phosphate may be reacted, or neutralized, bymixing the theoretical neutralizing quantities of the two components,heating above room temperature, care being taken not to exceedtemperature at which decomposition takes place, and then thoroughlymixing until reaction is complete. The reaction product is tested todetermine the degree of neutralization, and after neutralization isconfirmed as complete, said reaction product is then blended intogasoline as desired,

or may be blended into a small amount of gasoline to be used as agasoline concentrate. The aniline or homolog thereof may be added inwhatever order desired. However, the amine-alkyl acid phosphateneutralization product is insoluble in aniline and its homologs and as aconsequence thereof a one package additive is not practical.

Another procedure for manufacturing the novel reaction products whichinhibit corrosion comprises dissolving the amine or gasoline concentrateof amine in the gasoline to be treated, and then adding a predeterminedamount of alkyl acid phosphate. Alternately, the alkyl acid phosphatemay be added to the gasoline and then the requiredamount of amine added.The blend is-then mixed thoroughly for about a half-hour to insure.com-'plete reaction. A similar procedure may be followed for the preparationof a gasoline concentrate, should this be desired. The blend orconcentrate is then tested for degree of neutralization, and when foundto be satisfactory as evidenced by its non-precipitation or non-hazeformation, the aniline or its homolog, or a gasoline concentratethereof, may then be added and the gasoline thoroughly mixed forultimate use. I

It is an important qualification of the present process that the anilineor homolog thereof never be mixed with a blend containing the alkyl acidphosphate until all of the acidity of the alkyl acid phosphate has beenneutralized by the amine; To test the degree of neutralization, thefollowing procedure has been found to be effective. A drop of thereaction mixture is added to a 1% solution of aniline in aviationgasoline. If precepitation occurs on mixing then a small additionalquantity of the amine is added to the reaction mixture with continuedheating and agitation. This procedure is followed until anon-precipitating reaction product is finally formed from s mmers thealkyl acid phosphate and the branched chain dialkyl aliphatic amine.

The alkyl acid phosphates which may be used in the neutralization stepofthe presenhprocess arewthose'having from 8 to 16 carbonatoms per alleylgroup. 'Mainly :for commercial reasons, the preferred 'alkyltacidqahosphate is .Lorol 'acid;phospha-te, which isia mixture of thephosphoric esters of Lorol alcohol. 'lzhe'tterm "lrorol alcohol is usedin the .trade todenote a mixture of primary normal aliphatic alcohols-of8 to 12 carbon atoms which are obtained by fractionation of the alcoholsresulting from the reduction of cocoanut and/or palm kernel oils. Lorolacid phosphate mixtures are readily obtainable on the market andfor'this reason are preferred to the more :purified esters of 'greaterscarcity and higher price. 'Gne Lorol acid phosphate is sldunderthetrade name Ortholeum 1'62 and is-understood to be mainlya'mixture of mono and di acid phosphates of *Izorol alcohol. Though forthe reasons stated above -Lorol" acidpho'sphates arepreferred;other'alkyl' acid'phosphates containing "from8 to16carbon'a'toms peralkyl'group' are satisfactory. For *example, acommercial grade at n-octyl acid phosphate was found"to producean'excllent reaction; product.

'Toform the desired neutralization *productfthe proper proportions ofbranched chain "dialkyl aliphatic'amineand alkyl acid phosphate "mayreadily be determined by an electrometric titration of a sample "of thealkyl "acid phosphate withaqueousKOH' solution to 'a'pHofabout"9.From'the "amount of KOH used the quantity of amine required toneutralize the acid radicals .of thephosphate may 'easily'be calculated.'It is always desirable to have a's'light excess .of'amine present, andgood results have been obtained with 'asmuch as 50% excess of branchedchain dialkyl aliphatic amine.

In order to prevent corrosion effectively, the lower concentration'limitof the reaction product with respect'to thefinished gasoline should'beabout 0.002% by weight. This was determined by means of ASTMTD66'5"47Tcorrosion test modified to a bath temperature of'80--8'2"F. The upperconcentration limit is determined by that amount .ofneutralizationproduct which would cause engine deterioration due to the excessivequantity of phosphates thenpresent. Theupper limit is about'0.05'% byweight.

Certain embodiments of the present invention are more fully illustratedby the following examples:

Example I lntoa suitable vesselequipped-with meansifor heating,agitating, and cooling the-charge, there .are introduced 110 ,parts ofdi (secondary butyl) amine followedgra'duallyby 150.parts of a mixtureof mono and-di .Lorol acid-phosphates.(Ortholeum .162). .Themixture isza'gitatedivigorouslyandcooled as required to keep the temperature:below 200 F. The'reaction is =vigorous=and exothermic, consequently'therate of addition ofthe-phosphate is controlled to avoid 'exeeeding'theabove temperature limit. The'resulting mixture is stirred for aboutlhour at 140 F. 'Thereactionproductis aviscous,'*oily liquid, yellow "incolor.

The reaction product is then tested for neutrality :by means "of theaforementioned neutralization-test, and, if found to'be acid, additionalbranched chain dialkyl :aliphatic amine is added.

Finally, fivepounds of the finished additive=are added to 17,000 gallonsof aviation gasoline in a blender and agitatedrfor about '15 minutes.Then 1020pounds of mixed xylidiues are added and the mixture resultingtherefromis agitated for about .a halfrhour. 'Ther'final gasoline iscompletely homogeneous; free from haze, corrosionfresistant, and has arich mixture anti-knockratiug commensurate with the amount of xylidines*used.

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4 Example II A 10% by weight solution in gasoline of the finishedadditive from Example I is prepared by dissolving pounds of the reactionproduct in 900 pounds of gasoline in a mixer. The gasoline additiveconcentrate is thoroughly mixed for about onehour, and 50 pounds of thisconcentrate then blended into 111,000 gallons of aviation gasoline. Theresulting mixture is agitated for about 15 minutes. Finally,'1'020'.pounds of mixed xylidines are added and mixing continuedforanadditional 30.niinutes. This finished product is comparable to thatobtained in Example'I.

"Example *II] To 17,000 gallons of "aviation "gasoline in a blender areadded 7.10 lbs. of di (2,5,8-trimethyl dodecyl) amine. The resultingmixture is thoroughly agitated for about 10minutes, and then 2.68 poundsof a mixture of mono and di Lorol acid phosphate (Ortholeum 162) areadded with-continued mixing for about one-half hour. After'the"neutralization tests indicate the productionof a satisfactoryreact-ionproduct, 1020 pounds of mono methyl aniline are added and agitationcontinued for another half-hour. As in the former examples, testsindicate the "production of 'excellent quality "finished gasoline.

Example IV Alkylatepercent '70-88 Aromatics do '5-16 Isopentane do..5-14 Tetra.ethyl.lead.. -cc. per gallon 4 nevertheless, th'elinventionin its broadest scope-comprehends the treatment of-anymotor.fuel.Similarly, it willhe -appreciated that the-reaction: product of thepresent invention may be blended in proper proportions any desiredgasoline with the advantage .that 'the purchaser or user may add anysuitable amount of auilineor homologs thereoflfor the purposeof=obtaining rich mixture anti-'knoekmroperties', without difiicultiesiarisingfrom preeipitation ofrhaze formation which isgenerallyencountered*=when 'le'ss*satisfactory-corrosion inhibitorsareiuse'd.

It will now betapparent that l havetdevised'a 'novel -and usefulprocess'an'd composition of matter which embodies the features I ofadvantageenumerated as desirable. in' the statementof the-invention andthe abovedescr'iptionand while"in"'the-' present "instance "there aredescribed the preferred embodiments 't'l'iereot' *whi'c'h *h'ave beenfound 'in practice to give-satisfactory and-reliable results, it'istoT'be understood that "t'hc same is susceptible of modification invarious particulars without departing from the spirit or scope of 'thei'nvention-or sacrificing any of its =advantages.

1.. Acompletelyhomogeneous, corrosion-resistant avi-ation' ful havingaliigh "rich mixture anti-knock rating,comprisinggasoline"containing-'sufiicient aromatic amine from the "groupconsisting of aniline and-'homologs of aniline tosubstantially increasethe *rich mixture antikno'k properties (itthe'gas'oline-andbetween-0002922 and 0.05% by weight of the finishedgasoline of the addition product resulting from contacting an alkyl acidphosphate having from 8 to 16 carbon atoms per alkyl group with between100% and 150% of the quantity theoretically required to neutralize saidphosphate of a branched chain dialkyl aliphatic amine having 4-15 carbonatoms per alkyl group and in which each branch is a methyl groupattached to a carbon atom positioned at least two carbon atoms from theterminal carbon.

2. An anti-corrosive gasoline as in claim 1 wherein the branched chaindialkyl aliphatic amine is di (secondary butyl) amine.

3. An anti-corrosive gasoline as in claim 1 wherein the branched chaindialkyl aliphatic amine is di (2,5,8- trimethyl dodecyl) amine.

4. An anti-corrosive gasoline as in claim 1 wherein the branched chaindialkyl aliphatic amine is di (3-methyl pentyl) amine.

5. The method of simultaneously improving the anticorrosive and the richmixture anti-knock properties of a gasoline, which comprises forming insaid gasoline a corrosion inhibiting amount of the addition product ofan alkyl acid phosphate having 8 to 16 carbon atoms per alkyl group anda branched chain dialkyl aliphatic amine having 415 carbon atoms peralkyl group and in which each branch is a methyl group attached to acarbon atom positioned at least two carbon atoms from the terminalcarbon and in which all the acid hydrogen of said phosphate isneutralized by said amine, then adding suflicient aromatic amine fromthe group consisting of aniline and homologs of aniline to substantiallyincrease the rich mixture anti-knock properties.

6. The method of inhibiting the formation of an insoluble precipitatewhen an amine-phosphate corrosion inhibitor is added to a gasolinecontaining an aniline octane booster, which comprises adding to agasoline an alkyl acid phosphate having 8 to 16 carbon atoms per alkylgroup, adding between and about of the quantity theoretically requiredto neutralize all the acid hydrogen of said phosphate of a branchedchain dialkyl aliphatic amine having 4-l5 carbon atoms per alkyl groupand in which each branch is a methyl group attached to a carbon atompositioned at least two carbon atoms from the terminal carbon therebyforming in said gasoline an addition product of said amine with saidphosphate, then adding sufiicient aromatic amine from the groupconsisting of aniline and homologs of aniline to substantially increasethe rich mixture anti-knock properties of the gasoline, the amounts ofthe amine and the phosphate being such as to produce an addition productof between 0.002% and 0.05 by weight of the finished gasoline.

References Cited in the file of this patent UNETED STATES PATENTS2,297,114 Thompson Sept. 29, 1942 2,413,262 Stirton Dec. 24, 19462,413,852 Turner Ian. 7, 1947 2,550,982 Eberz May 1, 1951 FOREIGNPATENTS 225,547 Germany Nov. 2, 1942

1. A COMPLETELY HOMOGENEOUS, CORROSION-RESISTANT AVIATION FUEL HAVING AHIGH RICH MIXTURE ANTI-KNOCK RATING, COMPRISING GASOLINE CONTAININGSUFFICIENT AROMATIC AMINE FROM THE GROUP CONSISTING OF ANILINE ANDHOMOLOGS OF ANILINE TO SUBSTANTIALLY INCREASE THE RICH MIXTURE ANTIKNOCKPROPERTIES OF THE GASOLINE AND BETWEEN 0.002% AND 0.05% BY WEIGHT OF THEFINISHED GASOLINE OF THE ADDITION PRODUCT RESULTING FROM CONTACTING ANALKYL ACID PHOSPHATE HAVING FROM 8 TO 16 CARBON ATOMS PER ALKYL GROUPWITH BETWEEN 100% AND 150% OF THE QUANTITY THEORETICALLY REQUIRED TONEUTRALIZED SAID PHOSPHATE OF A BRANCHED CHAIN DIALKYL ALIPHATIC AMINEHAVING 4-15 CARBON ATOMS PER ALKYL GROUP AND IN WHICH EACH BRANCH IS AMETHYL GROUP ATTACHED TO A CARBON ATOM POSITIONED AT LEAST TWO CARBONATOMS FROM THE TERMINAL CARBON.